CVE-2026-124951: Firefox privilege escalation in Nimbus Desktop Client

CVE-2026-124951 · Severity: info · Published 2026-11-10

Firefox, a web browser used by millions of users worldwide, contains a privilege escalation vulnerability in its Nimbus Desktop Client component. An attacker could exploit this to gain elevated system permissions on an affected machine, potentially leading to complete system compromise or installation of malware with administrative privileges.

Technologies: Mozilla Firefox, Mozilla Firefox ESR. Vendors: Mozilla.

Quick answers

Is CVE-2026-124951 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-124951 being exploited in the wild.
How severe is CVE-2026-124951?
Informational severity, published 10 November 2026.
Which products and versions are affected?
Mozilla Firefox; Mozilla Firefox ESR.
Is there a fix for CVE-2026-124951?
Yes: fixed in Firefox 160, Firefox ESR 153.7. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-124951 attacked?
It is in a web application.
Am I affected by CVE-2026-124951?
Check whether you run Mozilla Firefox or Mozilla Firefox ESR. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: Firefox 160, Firefox ESR 153.7

Technical details

A privilege escalation vulnerability exists in Firefox's Nimbus Desktop Client component. The vulnerability allows an attacker with local or network access to elevate privileges beyond the intended security boundaries. The fix is available in Firefox 160 and Firefox ESR 153.7.

Affected products

  • Mozilla Firefox
  • Mozilla Firefox ESR

Timeline

  • 2026-11-10: disclosed

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.